The present invention relates to a straw and chaff spreader for use with a combine to broadcast straw and chaff to the rear and opposite sides of the combine after the threshing operation.
When a conventional combine is used for harvesting grain, such as wheat, the combine machine first cuts the wheat and conveys the stalks and wheat heads upwardly into the combine. A threshing mechanism is used to separate the grain from the wheat stalk. The grain is then conveyed by the combine to a series of sieves where the chaff is blown away from the grain by blasts of air. The grain separated from the chaff is then conveyed within the combine to a grain chute while the straw stalks and chaff are typically conveyed or blown rearwardly to fall upon the ground through a rear straw and chaff outlet chute. In the absence of some mechanism for spreading the straw and chaff, the straw and chaff typically falls into a windrow trailing behind the combine harvester. These windrows create problems for farmers who generally have to use other equipment for spreading or collecting the straw to remove the windrows.
A known method of spreading straw and chaff which is better than the old method of typically allowing the straw and chaff to just exit the outlet chute onto the ground is the use of circular spreader plates rotatably mounted at the rear of the combine beneath the combine""s rear straw and chaff outlet chute. U.S. Pat. No. 4,617,942 to Garner illustrates this method. Such spreader plates typically have spreader fins extending upwardly from their upper surfaces. The orientation of the fins and the direction of rotation of the counter-rotating spreader plates is selected to propel the straw and chaff rearwardly away from the harvester combine. With this equipment, the straw and chaff is blown rearwardly in a relatively concentrated stream resulting in undesirable accumulation of the straw and chaff behind the harvester combine.
Another straw and chaff spreader assembly is described in U.S. Pat. No. 5,976,011 to Hartman. In this assembly, the fins are again mounted on top of the counter-rotating spreader plates but the direction of rotation and the orientation of the fins are selected to propel the straw and chaff forwardly against a deflecting shield fixedly mounted on the rearward end of the harvester combine. The straw and chaff is directed by the rotating fins in a direction against the directional flow of the straw and chaff exiting the straw and chaff chute, and directs the straw and chaff to either side of the combine.
The present invention is an improvement over the straw and chaff spreader assemblies presently known. The direction of rotation of the straw spreaders and the orientation of the fins are selected such that the straw and chaff is moved rearwardly in the same direction as the straw and chaff exiting the straw and chaff chute. The straw and chaff is further propelled by the rotating fins against a rear deflector plate mounted to the combine. This structure propels the straw and chaff to either side of the combine a substantially large distance by combining the force of the flow of the straw and chaff being conveyed to the spreader plates with the force provided by the rotating fins. The even and wider spreading of the straw and chaff resulting from the use of this invention has several distinct advantages over the prior art spreaders. With the present invention, there is better germination of seeds, better cultivation conditions, better seed-to-soil contact, less trash interference with chemicals, more even drying of the soil, better warm-up of the soil, and less mold and other diseases which can cause crop yield losses.
A straw and chaff spreader includes a pair of counter-rotating spreader plates having fan-shaped blades attached to the top surface of each spreader plate. The spreader plates are located beneath the straw and chaff chute of a combine. A rear shield is mounted to the combine to the rear of the spreader plates. The shape of the blades and the direction of rotation of the spreader plates are selected to throw the straw and chaff received from the straw and chaff chute against the rear shield to propel the straw and chaff outwardly on either side of the combine.